This invention relates in general to universal joints and in particular to an improved yoke having grooves formed in its outer surface for providing access for a tool used to assemble the universal joint.
Universal joints are well known devices which provide a driving connection between two members adapted to rotate about non-aligned axes of rotation. Universal joints of this type are widely used between rotatable driveshafts in vehicle drive train systems. Typically, such universal joints include a cross having a central body portion with four trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A bearing cup is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between each of the trunnions and its associated bearing cup to permit the bearing cup to rotate relative to the trunnion. One pair of opposed bearing cups is connected to a first yoke secured to the first rotatable shaft, while the other pair of opposed bearing cups is connected to a second yoke secured to the second rotatable shaft.
In a typical vehicle drive train assembly, a first universal joint is used to connect a first end of the tubular main driveshaft to the output shaft of the transmission. A second universal joint is used to connect the opposite end of the driveshaft to the pinion shaft of the differential. Typically, the yoke secured to each end of the driveshaft is referred to as a "tube yoke." The yoke attached to either the transmission output shaft or the differential pinion shaft is usually referred to as an "end yoke." The tube yoke and the end yoke are similarly constructed in that they both have a generally cylindrical body portion having a sleeve portion extending axially in one direction and a pair of yoke arms extending axially in the opposite direction. In both the tube yoke and the end yoke, the rotatable shaft is secured to the sleeve portion. The structure of the end yoke often differs from the tube yoke in the construction of the yoke arms. Typically, each yoke arm of a tube yoke has a cylindrical opening formed therein for receiving and completely enclosing a bearing cup secured on the end of a trunnion of the universal joint cross. Thus, this type of tube yoke is referred to as a "full round" tube yoke. However, in some types of end yokes, each yoke so arm has a semi-cylindrical recess formed therein for receiving and only partially enclosing a bearing cup. A strap having a corresponding semi-cylindrical surface or a U bolt is used to complete the cylindrical opening and fully enclose the bearing cup. Typically, the retaining straps are secured to the yoke arms by threaded fasteners.
During assembly of the universal joint used to connect the driveshaft to the differential pinion shaft, the sleeve portion of a full round tube yoke is secured to the driveshaft tube and the sleeve portion of the half round end yoke is secured to the differential pinion shaft. The yoke arms of the full round tube yoke are connected to respective bearing cups mounted on a first pair of opposed trunnions of the universal joint cross. The second pair of opposed trunnions of the universal joint cross are aligned within the semi-cylindrical recess formed in the yoke arms of the half round end yoke. The retaining straps are then secured to the half round end yoke by the threaded fasteners.
In the past, the diameter of the driveshaft tube and the full round tube yoke were small enough that a conventional pneumatic nut runner or other suitable tool could be used to tighten the retaining strap threaded fasteners into the half round end yoke. In some vehicles, however, the diameter of the driveshaft tube and the full round tube yoke are increased to avoid critical speed vibrations and noise. It has been found that the increased diameter of the full round end yoke blocks the access for the nut runner to tighten the threaded fasteners, thus requiring a less desirable alternative tool or threading process. Ideally, it would be desirable to modify the larger diameter full round tube yoke such that conventional tools can still be used to secure the retaining straps to the half round end yoke used in the universal joint.